GH treatment and its effect on bone mineral density, bone maturation and growth in short children born small for gestational age: 3-year results of a randomized, controlled GH trial.

BACKGROUND

To investigate in a group of short children born small for gestational age (SGA), the effects of 3 years of GH treatment vs. no treatment on bone age (BA), height and bone mineral density (BMD). Also, to evaluate the influence of the severity of growth retardation at start and the GH dose on the gain in height.

PATIENTS AND METHODS

The study design was an open-labelled, controlled multicentre GH study for 3 years. Non-GH-deficient (GHD) children (n = 87) were randomized to either a GH group (n = 61) or an untreated control group (n = 26). In addition, 12 SGA children had GHD (GHD group) and were treated in parallel. Both the GH and the GHD group were treated with a GH dose of 33 microg/kg/day. BMD was evaluated using dual energy X-ray absorptiometry (DEXA). In addition, data of our first GH trial in which short SGA children were treated with a GH dose of 66 microg/kg/day (n = 24) were used for comparison of height gain.

RESULTS

In contrast to the control group, the GH group showed a significant increase in height (P < 0.001), as did the parallel GHD group. Bone maturation [delta bone age (BA)/delta calendar age (CA)] increased significantly during the first 2 years of GH treatment but slowed-down thereafter. The 3-year deltaBA/deltaCA ratio correlated significantly with the gain in height (r = 0.6, P < 0.001). At start, mean BMD SDS and mean BMAD SDS were significantly lower than zero. During GH treatment both increased impressively (P < 0.001). The gain in height of children with severe short stature at start (< or = -3.00 SDS), did not differ between those receiving either a GH dose of 33 or 66 microg/kg/day.

CONCLUSION

Three years of GH treatment in short children born SGA results in a normalization of height during childhood. Also, bone maturation increased proportionately to the height gain. At start, mean values of BMD and BMAD were significantly reduced but normalized during GH treatment. We did not find an indication to treat very short SGA children (H SDS < or = -3.00) with a higher GH dose. We rather suggest to start GH treatment at an early age in order to achieve a normal height before puberty starts.